The Effects of Obesity on the Cardiopulmonary System: Implications for Critical Care Nursing

Kim Garrett, RN, MS, CNP; Kathy Lauer, RN, PhD; Beth-Anne Christopher, RN, MS

Disclosures

Prog Cardiovasc Nurs. 2004;19(4) 

In This Article

Etiology of Obesity

The etiology of obesity involves an imbalance between caloric intake and caloric expenditure. Although the mechanisms underlying this discrepancy are not well understood, there is general agreement that the etiology of obesity is multifactorial and involves genetic, environmental, physiological, psychological, and sociocultural factors.[1,2,3]

The fact that there is a familial pattern to obesity suggests a genetic cause. More evidence of a genetic factor derives from adoption studies showing that adopted children had body weights more correlated to their biological parents.[6] However, genetic change within a population occurs slowly, and the recent explosion in the incidence of obesity suggests primarily nongenetic factors.

Families share genetics, diet, eating patterns, and overall lifestyles, all of which may contribute to obesity. American adults tend to eat foods that are high in carbohydrates and fats, much of which is "fast food." In addition, portion size has increased. In contrast, American adults are sedentary and physical activity is often inadequate, particularly in light of the increased caloric intake.[5,6]

Individual factors, both physiological and psychological, may also influence the development of obesity. Physiological factors may include: 1) abnormalities of the satiety center in the hypothalamus caused by trauma or disease; 2) rare genetic endocrine disorders such as Prader-Willi syndrome and Laurence-Moon (Bardet-Biedl) syndrome; 3) endogenous hypersecretion of glucocorticoids, as occurs in Cushing's syndrome and Cushing's disease; 4) hypothyroidism; 5) administration of exogenous glucocorticoids for a wide variety of conditions; and 6) selected medications, including insulin, oral hypoglycemic agents, and certain antidepressants.[1,2] Psychological factors influencing the development of obesity involve the use of food in response to strong emotions, often negative ones. For example, individuals who are depressed often experience changes in appetite that often result in overeating and obesity.

Sociocultural factors, including socioeconomic status, educational level, and stigma are implicated in the increase in the incidence of obesity. Individuals in lower socioeconomic groups and those with less education have increased obesity rates.[5] Inadequate financial resources may restrict the types of foods an individual can afford; high-fat, high-carbohydrate foods are generally cheaper than more nutritious foods. As a result, grocery stores in poorer communities stock what their customers usually buy, and customers may not even have the option to buy foods with more nutritional value. In addition, support groups and formal exercise or activity programs for the obese are less accessible in low-income areas and groups. Similarly, less education may prevent individuals from understanding "good nutrition," the balance necessary between caloric intake and expenditure, and the beneficial effect of exercise. Lastly, the degree of stigma and discrimination attached to obesity varies within and between cultural/ethnic groups. This variation may be associated with greater or lesser degrees of obesity among group members.

Clearly, the etiology of obesity is complex and multidimensional; however, the fundamental imbalance between caloric intake and caloric expenditure is what results in an abnormal increase in the number and size of fat cells. It appears that substances secreted from these fat cells produce most of the pathological changes that result in complications; the rest are the result of the mass of fat itself.[13] Most of the health-related problems and the increased risk of death in obese individuals are due to cardiovascular causes.[13] The remainder of this article focuses on the effects of obesity on the cardiopulmonary system.

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